JP2020186149A - METHOD FOR PRODUCING MnZn-BASED FERRITE POWDER - Google Patents
METHOD FOR PRODUCING MnZn-BASED FERRITE POWDER Download PDFInfo
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- 229910000859 α-Fe Inorganic materials 0.000 title claims abstract description 115
- 239000000843 powder Substances 0.000 title claims abstract description 90
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 48
- 238000005245 sintering Methods 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000000465 moulding Methods 0.000 claims abstract description 8
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 5
- 239000002245 particle Substances 0.000 claims description 38
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 31
- 229910052760 oxygen Inorganic materials 0.000 claims description 31
- 239000001301 oxygen Substances 0.000 claims description 31
- 238000010298 pulverizing process Methods 0.000 claims description 23
- 230000008569 process Effects 0.000 claims description 15
- 238000009826 distribution Methods 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 229910020599 Co 3 O 4 Inorganic materials 0.000 claims description 9
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- 229910007541 Zn O Inorganic materials 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 4
- 238000000691 measurement method Methods 0.000 claims description 3
- 230000001186 cumulative effect Effects 0.000 claims description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract description 2
- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(II,III) oxide Inorganic materials [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 abstract 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 34
- 239000013078 crystal Substances 0.000 description 24
- 230000000694 effects Effects 0.000 description 18
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 16
- 239000011701 zinc Substances 0.000 description 9
- 239000011787 zinc oxide Substances 0.000 description 8
- 230000004907 flux Effects 0.000 description 7
- 229910052758 niobium Inorganic materials 0.000 description 7
- 229910052715 tantalum Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 230000035699 permeability Effects 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910017518 Cu Zn Inorganic materials 0.000 description 1
- 229910017752 Cu-Zn Inorganic materials 0.000 description 1
- 229910017943 Cu—Zn Inorganic materials 0.000 description 1
- 229910017082 Fe-Si Inorganic materials 0.000 description 1
- 229910017133 Fe—Si Inorganic materials 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 229910008458 Si—Cr Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 238000000399 optical microscopy Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000011802 pulverized particle Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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- Compounds Of Iron (AREA)
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Abstract
Description
本発明は、例えば、スイッチング電源等のトランス、チョークコイル等の機能素子である電子部品に用いるＭｎＺｎ系フェライト粉の製造方法に関する。 The present invention relates to, for example, a method for producing MnZn-based ferrite powder used for electronic components such as transformers such as switching power supplies and functional elements such as choke coils.
スイッチング電源は、ＥＶ（電気自動車）、ＨＥＶ（ハイブリッド電気自動車）、移動体通信機器（携帯電話、スマートフォン等）、パーソナルコンピュータ、サーバー等の電源供給が必要な様々な電子機器の電源回路で用いられる。 Switching power supplies are used in power circuits of various electronic devices that require power supply, such as EVs (electric vehicles), HEVs (hybrid electric vehicles), mobile communication devices (mobile phones, smartphones, etc.), personal computers, servers, etc. ..
最近の電子機器は、小型・軽量化とともに、エネルギー効率の観点から低消費電力であることがいっそう求められるようになってきた。そのため、電子機器に使用されるＤＳＰ（Ｄｉｇｉｔａｌ Ｓｉｇｎａｌ Ｐｒｏｃｅｓｓｏｒ）、ＭＰＵ（Ｍｉｃｒｏ−ｐｒｏｃｅｓｓｉｎｇ Ｕｎｉｔ）等のＬＳＩ（Ｌａｒｇｅ−Ｓｃａｌｅ Ｉｎｔｅｇｒａｔｉｏｎ）及び機能素子もまた小形・高性能化とともに低消費電力化が求められている。一方で、近年ＬＳＩは微細配線化によるトランジスタの高集積化に伴って、トランジスタの耐圧が低下するとともに消費電流が増加し、動作電圧の低電圧化及び大電流化が進んでいる。 In recent years, electronic devices have become more and more required to have low power consumption from the viewpoint of energy efficiency as well as to be smaller and lighter. Therefore, LSIs (Large-Scale Integration) such as DSPs (Digital Signal Processors) and MPUs (Micro-processing Units) used in electronic devices and functional elements are also required to be compact, have high performance, and have low power consumption. There is. On the other hand, in recent years, along with the high integration of transistors due to fine wiring, the withstand voltage of the transistors has decreased and the current consumption has increased, and the operating voltage has been lowered and the current has been increased.
ＬＳＩに電源を供給するＤＣ−ＤＣコンバータ等の電源回路もまた、ＬＳＩの動作電圧の低電圧化及び大電流化への対応が必要となる。例えば、ＬＳＩの動作電圧の低電圧化によって正常に動作する電圧範囲が狭くなるので、電源回路からの供給電圧の変動（リップル）によってＬＳＩの電源電圧範囲を上回ったり下回ったりしてしまうと、ＬＳＩの不安定動作を招くため、電源回路のスイッチング周波数を高め、例えば５００ｋＨｚ以上のスイッチング周波数とする対策が採られるようになった。 A power supply circuit such as a DC-DC converter that supplies power to an LSI also needs to cope with lowering the operating voltage of the LSI and increasing the current. For example, the voltage range for normal operation is narrowed by lowering the operating voltage of the LSI. Therefore, if the supply voltage fluctuation (ripple) from the power supply circuit causes the LSI to exceed or fall below the power supply voltage range of the LSI, the LSI In order to cause unstable operation of the power supply circuit, measures have been taken to increase the switching frequency of the power supply circuit so that the switching frequency is set to 500 kHz or higher, for example.
このような電源回路の高周波化や大電流化への対応は、回路に使用するトランス、チョークコイル等の電子部品を構成する磁心を小型化するメリットもある。例えばトランスを正弦波で駆動する場合、１次側コイルへの印加電圧Ｅｐ（Ｖ）は、１次側コイルの巻線数Ｎｐ、磁心の断面積Ａ（ｃｍ２）、周波数ｆ（Ｈｚ）及び励磁磁束密度Ｂｍ（ｍＴ）を用いて式：
Ｅｐ＝４．４４×Ｎｐ×Ａ×ｆ×Ｂｍ×１０−７
で現される。
Correspondence to such high frequency and large current of the power supply circuit also has an advantage of reducing the size of the magnetic core constituting the electronic component such as the transformer and the choke coil used in the circuit. For example, when the transformer is driven by a sine wave, the voltage Ep (V) applied to the primary coil is the number of windings Np of the primary coil, the cross-sectional area A (cm 2 ) of the magnetic core, the frequency f (Hz) and Equation using the exciting magnetic flux density Bm (mT):
Ep = 4.44 x Np x A x f x Bm x 10-7
Appeared in.
この式から、所定の１次側コイルへの印加電圧Ｅｐに対して、周波数（スイッチング周波数）ｆを高くすれば、磁心の断面積Ａを小さくできて小型となることがわかる。また、大電流化に伴って最大励磁磁束密度（以下、励磁磁束密度という）Ｂｍが高くなるのでいっそう磁心は小型化する。 From this equation, it can be seen that if the frequency (switching frequency) f is increased with respect to the voltage Ep applied to the predetermined primary coil, the cross-sectional area A of the magnetic core can be reduced and the size can be reduced. Further, the maximum exciting magnetic flux density (hereinafter referred to as the exciting magnetic flux density) Bm increases as the current increases, so that the magnetic core becomes smaller.
高周波数領域において高励磁磁束密度で動作し、かつ小型化に好適な磁心には、ＭｎＺｎ系フェライトが磁性材料として主に用いられる。ＭｎＺｎ系フェライトはＮｉ系フェライト等と比較して初透磁率や飽和磁束密度が大きく、Ｆｅ系、Ｃｏ系アモルファスや純鉄、Ｆｅ−Ｓｉ、Ｆｅ−Ｎｉ、Ｆｅ−Ｓｉ−Ｃｒ、Ｆｅ−Ｓｉ−Ａｌ等の金属系の磁性材料を使用する磁心等と比較しても磁心損失が小さいといった特徴を有している。磁心損失が小さいことは電源回路の消費電力を抑える点で有利である。
この高周波数領域用のＭｎＺｎ系フェライト磁心に関する記載が特許文献１にある。
MnZn-based ferrite is mainly used as a magnetic material for a magnetic core that operates at a high exciting magnetic flux density in a high frequency region and is suitable for miniaturization. MnZn-based ferrite has a higher initial magnetic permeability and saturation magnetic flux density than Ni-based ferrite, etc., and Fe-based, Co-based amorphous, pure iron, Fe-Si, Fe-Ni, Fe-Si-Cr, Fe-Si- It has a feature that the magnetic core loss is small as compared with a magnetic core or the like using a metallic magnetic material such as Al. The small magnetic core loss is advantageous in suppressing the power consumption of the power supply circuit.
Patent Document 1 describes a MnZn-based ferrite core for this high frequency region.
特許文献１には、１ＭＨｚ以上の高周波数領域で優れた磁気特性が得られるＭｎＺｎ系フェライト磁心に関する記載がある。しかしながら、特許文献１では、焼結体からなる磁心に関する記載のみである。焼結体からなる磁心の場合、形成できる形状にある程度制限があり、自由な形態の磁心を得るには課題があった。
特許文献２には、焼成した後、粉砕するフェライト粉末の製造方法であって、粉砕されたフェライト粉末をアニール処理するフェライト粉末の製造方法の記載がある。しかし、特許文献２には、詳細な粉砕方法の記載はなく、また、記載されているアニール処理は、熱処理温度が７００〜９５０℃、焼成時間が４時間という高温で長時間の熱処理である。更に、特許文献２のものは、Ｎｉ−Ｃｕ−Ｚｎ系フェライトであり、ＭｎＺｎ系フェライトとは異なる材料である。
Patent Document 1 describes a MnZn-based ferrite magnetic core capable of obtaining excellent magnetic characteristics in a high frequency region of 1 MHz or higher. However, Patent Document 1 only describes a magnetic core made of a sintered body. In the case of a magnetic core made of a sintered body, the shape that can be formed is limited to some extent, and there is a problem in obtaining a magnetic core in a free form.
Patent Document 2 describes a method for producing a ferrite powder that is fired and then pulverized, and is a method for producing a ferrite powder that anneals the pulverized ferrite powder. However, Patent Document 2 does not describe a detailed pulverization method, and the described annealing treatment is a long-time heat treatment at a high temperature of 700 to 950 ° C. and a firing time of 4 hours. Further, the material of Patent Document 2 is Ni—Cu—Zn-based ferrite, which is a material different from MnZn-based ferrite.
このため、５００ｋＨｚ以上の高周波数領域、特に１〜５ＭＨｚの高周波数領域で利用可能なＭｎＺｎ系フェライト粉が求められているが、それを得る方法は、明らかとはなっていなかった。
したがって本発明の目的は、５００ｋＨｚ以上、特に１〜５ＭＨｚの高周波数領域において、有用なＭｎＺｎ系フェライト粉が得られる、ＭｎＺｎ系フェライト粉の製造方法を提供することにある。
Therefore, there is a demand for MnZn-based ferrite powder that can be used in a high frequency region of 500 kHz or higher, particularly in a high frequency region of 1 to 5 MHz, but a method for obtaining the powder has not been clarified.
Therefore, an object of the present invention is to provide a method for producing MnZn-based ferrite powder, which can obtain useful MnZn-based ferrite powder in a high frequency region of 500 kHz or higher, particularly 1 to 5 MHz.
上記課題を解決するための具体的手段には、以下の態様が含まれる。
＜１＞ Ｆｅ２Ｏ３換算で５３〜５６モル％のＦｅ、ＺｎＯ換算で３〜９モル％のＺｎ及びＭｎＯ換算で残部Ｍｎを主成分として含み、前記酸化物換算での前記主成分の合計１００質量部に対して、Ｃｏ３Ｏ４換算で０．０５〜０．４質量部のＣｏを副成分として含むＭｎＺｎ系フェライト粉の製造方法であって、
ＭｎＺｎ系フェライトの原料粉末を成形して成形体を得る成形工程と、
前記成形体を焼結し、１５０℃未満の温度まで冷却しＭｎＺｎ系フェライトの焼結体を得る焼結工程と、
得られたＭｎＺｎ系フェライトの焼結体を粉砕してＭｎＺｎ系フェライト粉を得る粉砕工程と、を備え、
更に、前記ＭｎＺｎ系フェライトの焼結体を熱処理する熱処理工程と、前記ＭｎＺｎ系フェライトの焼結体を粉砕したＭｎＺｎ系フェライト粉を熱処理する熱処理工程とのうち、少なくとも一方の熱処理工程を備え、前記熱処理工程が、
条件１：２００℃以上、及び
条件２：（Ｔｃ−９０）℃〜（Ｔｃ＋１００）℃［ただし、Ｔｃは前記ＭｎＺｎ系フェライトの主成分に含まれるＦｅ２Ｏ３及びＺｎＯのモル％から計算により求められるキュリー温度（℃）である。］
を満たす温度まで加熱し、一定時間保持した後、前記保持温度から５０℃／時間以下の速度で降温する熱処理工程であることを特徴とするＭｎＺｎ系フェライト粉の製造方法。
Specific means for solving the above problems include the following aspects.
<1> Fe 2 O 3 equivalent 53 to 56 mol% Fe, ZnO equivalent 3 to 9 mol% Zn and MnO equivalent residual Mn as main components, and the total of the main components in terms of oxide. A method for producing MnZn-based ferrite powder containing 0.05 to 0.4 parts by mass of Co as a sub-component in terms of Co 3 O 4 with respect to 100 parts by mass.
The molding process of molding the raw material powder of MnZn-based ferrite to obtain a molded product,
A sintering step of sintering the molded product and cooling it to a temperature of less than 150 ° C. to obtain a sintered body of MnZn-based ferrite.
A pulverization step of pulverizing the obtained MnZn-based ferrite sintered body to obtain MnZn-based ferrite powder is provided.
Further, the heat treatment step of at least one of a heat treatment step of heat-treating the sintered body of the MnZn-based ferrite and a heat treatment step of heat-treating the MnZn-based ferrite powder obtained by crushing the sintered body of the MnZn-based ferrite is provided. The heat treatment process
Condition 1: 200 ° C. or higher, and Condition 2: (Tc-90) ° C. to (Tc + 100) ° C. [However, Tc is calculated from the molar% of Fe 2 O 3 and Zn O contained in the main component of the MnZn-based ferrite. Curie temperature (° C). ]
A method for producing MnZn-based ferrite powder, which comprises a heat treatment step of heating to a temperature satisfying the above conditions, holding for a certain period of time, and then lowering the temperature from the holding temperature at a rate of 50 ° C./hour or less.
＜２＞ 前記ＭｎＺｎ系フェライト粉は、レーザー回折散乱式粒度分布測定法により得られる体積基準粒度分布において、粒径１μｍの小粒径側からの通過分積算（％）が１５％以下となる粒度分布を備える、＜１＞に記載のＭｎＺｎ系フェライト粉の製造方法。
＜３＞ 前記ＭｎＺｎ系フェライト粉は、平均粒径Ｄ５０が１００μｍ以下である、＜１＞または＜２＞に記載のＭｎＺｎ系フェライト粉の製造方法。
<2> The MnZn-based ferrite powder has a particle size of 15% or less in terms of the volume-based particle size distribution obtained by the laser diffraction / scattering type particle size distribution measurement method. The method for producing an MnZn-based ferrite powder according to <1>, which comprises a distribution.
<3> The method for producing MnZn-based ferrite powder according to <1> or <2>, wherein the MnZn-based ferrite powder has an average particle size D50 of 100 μm or less.
＜４＞ 前記ＭｎＺｎ系フェライト粉は、前記酸化物換算での前記主成分の合計１００質量部に対して、副成分として更に、ＳｉＯ２換算で０．００３〜０．０１５質量部のＳｉ、ＣａＣＯ３換算で０．０６〜０．３質量部のＣａ、Ｖ２Ｏ５換算で０〜０．１質量部のＶ、並びに合計で０〜０．３質量部のＮｂ（Ｎｂ２Ｏ５換算）及び／又はＴａ（Ｔａ２Ｏ５換算）を含む、＜１＞〜＜３＞のいずれかに記載のＭｎＺｎ系フェライト粉の製造方法。 <4> The MnZn ferrite powder, the per 100 parts by weight of the main component in terms of oxide, further as an auxiliary component, Si of 0.003 to 0.015 parts by weight in terms of SiO 2, CaCO 0.06 to 0.3 parts by mass of Ca in 3 conversion, V of 0 to 0.1 parts by mass in V 2 O 5 conversion, and Nb of 0 to 0.3 parts by mass in total (Nb 2 O 5 conversion) The method for producing an MnZn-based ferrite powder according to any one of <1> to <3>, which comprises and / or Ta (Ta 2 O 5 conversion).
＜５＞ 前記焼結工程は、昇温工程と、高温保持工程と、降温工程とを有し、
前記高温保持工程は、保持温度が１０５０℃超１１５０℃未満で、雰囲気中の酸素濃度が０．４〜２体積％であり、
前記降温工程中、９００℃から４００℃まで降温させる際の酸素濃度を０．００１〜０．２体積％の範囲とし、（Ｔｃ＋７０）℃から１００℃までの間の降温速度を５０℃／時間以上とする、＜１＞〜＜４＞のいずれかに記載のＭｎＺｎ系フェライト粉の製造方法。
＜６＞ 前記降温工程中、前記保持温度から１００℃までの間の降温速度を５０℃／時間以上とする、＜５＞に記載のＭｎＺｎ系フェライト粉の製造方法。
<5> The sintering step includes a temperature raising step, a high temperature holding step, and a temperature lowering step.
In the high temperature holding step, the holding temperature is more than 1050 ° C and less than 1150 ° C, and the oxygen concentration in the atmosphere is 0.4 to 2% by volume.
During the temperature lowering step, the oxygen concentration when lowering the temperature from 900 ° C. to 400 ° C. is in the range of 0.001 to 0.2% by volume, and the temperature lowering rate between (Tc + 70) ° C. and 100 ° C. is 50 ° C./hour or more. The method for producing MnZn-based ferrite powder according to any one of <1> to <4>.
<6> The method for producing MnZn-based ferrite powder according to <5>, wherein the temperature lowering rate between the holding temperature and 100 ° C. is 50 ° C./hour or more during the temperature lowering step.
本発明によれば、５００ｋＨｚ以上の高周波数領域において、有用なＭｎＺｎ系フェライト粉が得られる。 According to the present invention, a useful MnZn-based ferrite powder can be obtained in a high frequency region of 500 kHz or higher.
本明細書において、「〜」を用いて表される数値範囲は、「〜」の前後に記載される数値を下限値及び上限値として含む範囲を意味する。本明細書において段階的に記載されている数値範囲において、一つの数値範囲で記載された上限値又は下限値は、他の段階的な記載の数値範囲の上限値又は下限値に置き換えてもよい。また、本明細書に記載されている数値範囲において、その数値範囲の上限値又は下限値は、実施例に示されている値に置き換えてもよい。
本明細書において、「工程」との語は、独立した工程だけでなく、他の工程と明確に区別できない場合であっても工程の所期の目的が達成されれば、本用語に含まれる。
以下、本発明の実施形態について説明するが、本発明は、以下に記載の実施形態に限定されるものではなく、技術的思想の範囲内で適宜変更可能である。
In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. .. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below, and can be appropriately modified within the scope of the technical idea.
本発明の一実施形態は、Ｆｅ２Ｏ３換算で５３〜５６モル％のＦｅ、ＺｎＯ換算で３〜９モル％のＺｎ及びＭｎＯ換算で残部Ｍｎを主成分として含み、前記酸化物換算での前記主成分の合計１００質量部に対して、Ｃｏ３Ｏ４換算で０．０５〜０．４質量部のＣｏを副成分として含むＭｎＺｎ系フェライト粉の製造方法であって、
ＭｎＺｎ系フェライトの原料粉末を成形して成形体を得る成形工程と、
前記成形体を焼結し、１５０℃未満の温度まで冷却しＭｎＺｎ系フェライトの焼結体を得る焼結工程と、
得られたＭｎＺｎ系フェライトの焼結体を粉砕してＭｎＺｎ系フェライト粉を得る粉砕工程と、を備え、
更に、前記ＭｎＺｎ系フェライトの焼結体を熱処理する熱処理工程と、前記ＭｎＺｎ系フェライトの焼結体を粉砕したＭｎＺｎ系フェライト粉を熱処理する熱処理工程とのうち、少なくとも一方の熱処理工程を備え、前記熱処理工程が、
条件１：２００℃以上、及び
条件２：（Ｔｃ−９０）℃〜（Ｔｃ＋１００）℃［ただし、Ｔｃは前記ＭｎＺｎ系フェライトの主成分に含まれるＦｅ２Ｏ３及びＺｎＯのモル％から計算により求められるキュリー温度（℃）である。］
を満たす温度まで加熱し、一定時間保持した後、前記保持温度から５０℃／時間以下の速度で降温する熱処理工程であることを特徴とするＭｎＺｎ系フェライト粉の製造方法である。
One embodiment of the present invention contains 53 to 56 mol% of Fe in terms of Fe 2 O 3 , 3 to 9 mol% of Zn in terms of ZnO, and the balance Mn in terms of MnO as main components, and in terms of the oxide. A method for producing MnZn-based ferrite powder containing 0.05 to 0.4 parts by mass of Co as a sub-component in terms of Co 3 O 4 with respect to 100 parts by mass of the total of the main components.
The molding process of molding the raw material powder of MnZn-based ferrite to obtain a molded product,
A sintering step of sintering the molded product and cooling it to a temperature of less than 150 ° C. to obtain a sintered body of MnZn-based ferrite.
A pulverization step of pulverizing the obtained MnZn-based ferrite sintered body to obtain MnZn-based ferrite powder is provided.
Further, the heat treatment step of at least one of a heat treatment step of heat-treating the sintered body of the MnZn-based ferrite and a heat treatment step of heat-treating the MnZn-based ferrite powder obtained by crushing the sintered body of the MnZn-based ferrite is provided. The heat treatment process
Condition 1: 200 ° C. or higher, and Condition 2: (Tc-90) ° C. to (Tc + 100) ° C. [However, Tc is calculated from the molar% of Fe 2 O 3 and Zn O contained in the main component of the MnZn-based ferrite. Curie temperature (° C). ]
A method for producing MnZn-based ferrite powder, which comprises a heat treatment step of heating to a temperature satisfying the above conditions, holding the powder for a certain period of time, and then lowering the temperature from the holding temperature at a rate of 50 ° C./hour or less.
［１］組成
この実施形態のＭｎＺｎ系フェライトの組成について、以下に記載する。
ＭｎＺｎ系フェライトはＦｅ、Ｚｎ及びＭｎを所定の範囲として、所望の初透磁率、飽和磁束密度等の磁気特性を得る。更に、副成分としてＣｏを加えて結晶磁気異方性定数の調整を行うことで、磁心損失の温度特性を改善することができる。
[1] Composition The composition of the MnZn-based ferrite of this embodiment is described below.
The MnZn-based ferrite obtains magnetic characteristics such as desired initial magnetic permeability and saturated magnetic flux density with Fe, Zn and Mn in a predetermined range. Further, by adding Co as a sub-component to adjust the crystal magnetic anisotropy constant, the temperature characteristic of the magnetic core loss can be improved.
本実施形態のＭｎＺｎ系フェライトは、主成分としてＦｅ、Ｚｎ及びＭｎを含み、副成分として少なくともＣｏを含み、前記主成分が、Ｆｅ２Ｏ３換算で５３〜５６モル％のＦｅ、ＺｎＯ換算で３〜９モル％のＺｎ及びＭｎＯ換算で残部Ｍｎからなり、前記副成分が、前記酸化物換算での主成分の合計１００質量部に対して、Ｃｏ３Ｏ４換算で０．０５〜０．４質量部のＣｏを含む。副成分は、更に、前記酸化物換算での主成分の合計１００質量部に対して、ＳｉＯ２換算で０．００３〜０．０１５質量部のＳｉ、ＣａＣＯ３換算で０．０６〜０．３質量部のＣａ、Ｖ２Ｏ５換算で０〜０．１質量部のＶ、並びに合計で０〜０．３質量部のＮｂ（Ｎｂ２Ｏ５換算）及び／又はＴａ（Ｔａ２Ｏ５換算）を含んでもよい。 The MnZn-based ferrite of the present embodiment contains Fe, Zn and Mn as main components and at least Co as sub-components, and the main component is 53 to 56 mol% of Fe and ZnO in terms of Fe 2 O 3. It consists of 3 to 9 mol% of Zn and the balance Mn in terms of MnO, and the sub-component is 0.05 to 0. 0 in terms of Co 3 O 4 with respect to a total of 100 parts by mass of the main component in terms of oxide. Contains 4 parts by mass of Co. Further, the sub-components are 0.003 to 0.015 parts by mass of Si in terms of SiO 2 and 0.06 to 0.3 in terms of CaCO 3 with respect to a total of 100 parts by mass of the main component in terms of oxide. Ca, V 2 O 5 by mass 0 to 0.1 parts by mass V, and 0 to 0.3 parts by mass Nb (Nb 2 O 5 conversion) and / or Ta (Ta 2 O 5 conversion) in total ) May be included.
ＦｅはＣｏとともに磁心損失の温度特性を制御する効果を有し、量が少なすぎると、磁心損失が極小となる温度が高温になりすぎ、量が多すぎると、磁心損失が極小となる温度が低温になりすぎ、磁心損失が極小となる温度を２０〜１００℃の間とするのが困難で、０〜１２０℃における磁心損失が劣化する。Ｆｅ含有量が、Ｆｅ２Ｏ３換算で５３〜５６モル％の間であれば、１ＭＨｚ以上の高周波数領域で低損失とすることができる。Ｆｅ含有量は、更に好ましくはＦｅ２Ｏ３換算で５４〜５５モル％である。 Fe has the effect of controlling the temperature characteristics of the magnetic core loss together with Co. If the amount is too small, the temperature at which the magnetic core loss is minimized becomes too high, and if the amount is too large, the temperature at which the magnetic core loss is minimized becomes too high. It becomes too low, and it is difficult to set the temperature at which the magnetic core loss is minimized between 20 and 100 ° C., and the magnetic core loss at 0 to 120 ° C. deteriorates. If the Fe content is between 53 and 56 mol% in terms of Fe 2 O 3 , low loss can be achieved in a high frequency region of 1 MHz or more. The Fe content is more preferably 54 to 55 mol% in terms of Fe 2 O 3 .
Ｚｎは透磁率の周波数特性を制御する効果を有し、磁心損失においては磁壁共鳴などの損失に係る残留損失の制御に特に影響を及ぼし、量が少ないほどより高周波数領域での磁心損失が低くなる。Ｚｎ含有量が、ＺｎＯ換算で３〜９モル％であれば１ＭＨｚ以上の高周波数領域、特に３ＭＨｚまでの周波数領域で低損失とすることができる。Ｚｎ含有量は、更に好ましくはＺｎＯ換算で５〜８モル％である。
ＭｎはＭｎＯ換算で残部となる。
Zn has the effect of controlling the frequency characteristics of magnetic permeability, and has a particular effect on the control of residual loss related to loss such as domain wall resonance in magnetic core loss. The smaller the amount, the lower the magnetic core loss in the high frequency region. Become. If the Zn content is 3 to 9 mol% in terms of ZnO, low loss can be achieved in a high frequency region of 1 MHz or higher, particularly in a frequency region of up to 3 MHz. The Zn content is more preferably 5 to 8 mol% in terms of ZnO.
Mn is the balance in terms of MnO.
Ｆｅ２Ｏ３及びＺｎＯのモル％から計算により求められるキュリー温度（Ｔｃ）は、Ｆｅ含有量及びＺｎ含有量が上記範囲であれば２５０〜３３０℃の範囲となり実用上差し支えのない温度である。 The Curie temperature (Tc) calculated from the mol% of Fe 2 O 3 and Zn O is in the range of 250 to 330 ° C. if the Fe content and the Zn content are in the above ranges, which is a temperature that does not pose a practical problem.
本実施形態のＭｎＺｎ系フェライトは、副成分として少なくともＣｏを含む。Ｃｏ２＋はＦｅ２＋とともに正の結晶磁気異方性定数Ｋ１を有する金属イオンとして、磁心損失が最小となる温度を調整する効果を有し、更にＦｅ２＋に比べ大きな結晶磁気異方性定数Ｋ１を有することから、磁心損失の温度依存性を改善するのに有効な元素である。量が少なすぎると温度依存性を改善する効果が少なく、量が多すぎると低温度域での損失の増加が著しく、実用上好ましくない。またＣｏ含有量が前記酸化物換算での前記主成分の合計１００質量部に対してＣｏ３Ｏ４換算で０．０５〜０．４質量部であれば、熱処理によってＦｅ２＋イオンとともにＣｏ２＋イオンを再配列させ誘導磁気異方性を制御することにより、実用温度範囲で磁心損失をいっそう低減でき、かつ温度依存性を改善することができる。Ｃｏ含有量は、更に好ましくはＣｏ３Ｏ４換算で０．１〜０．３質量部である。 The MnZn-based ferrite of the present embodiment contains at least Co as a sub-component. Co 2+ has the effect of adjusting the temperature at which the magnetic core loss is minimized as a metal ion having a positive magnetocrystalline anisotropy constant K1 together with Fe 2+ , and further has a large magnetocrystalline anisotropy constant K1 as compared with Fe 2+. Since it has, it is an effective element for improving the temperature dependence of magnetic core loss. If the amount is too small, the effect of improving the temperature dependence is small, and if the amount is too large, the loss increases significantly in the low temperature range, which is not practically preferable. Further, if 0.05 to 0.4 parts by weight of Co 3 O 4 conversion per 100 parts by weight of the main component in the Co content is the terms of oxide, Co 2+ ions with Fe 2+ ions by heat treatment By rearranging and controlling the induced magnetic anisotropy, the magnetic core loss can be further reduced in the practical temperature range, and the temperature dependence can be improved. The Co content is more preferably 0.1 to 0.3 parts by mass in terms of Co 3 O 4 .
副成分として更にＣａ及びＳｉを含むのが好ましい。Ｓｉは粒界に偏析し粒界抵抗を高め、渦電流損失を低減し、もって高周波数領域における磁心損失を低減させる効果を有し、量が少なすぎると粒界抵抗を高める効果が少なく、量が多すぎると逆に結晶の肥大化を誘発し磁心損失を劣化させる。Ｓｉ含有量が、前記酸化物換算での前記主成分の合計１００質量部に対してＳｉＯ２換算で０．００３〜０．０１５質量部であれば渦電流損失を低減するに十分な粒界抵抗を確保でき、１ＭＨｚ以上の高周波数領域で低損失とすることができる。Ｓｉ含有量は、更に好ましくはＳｉＯ２換算で０．００５〜０．０１質量部である。 It is preferable that Ca and Si are further contained as auxiliary components. Si segregates at the grain boundaries to increase the grain boundary resistance, reduce the eddy current loss, and thus have the effect of reducing the magnetic core loss in the high frequency region. If the amount is too small, the effect of increasing the grain boundary resistance is small, and the amount On the contrary, if the amount is too large, the crystal enlargement is induced and the magnetic core loss is deteriorated. If the Si content is 0.003 to 0.015 parts by mass in terms of SiO 2 with respect to 100 parts by mass of the total of the main components in terms of oxides, the grain boundary resistance is sufficient to reduce the eddy current loss. Can be secured, and low loss can be achieved in a high frequency region of 1 MHz or higher. The Si content is more preferably 0.005 to 0.01 parts by mass in terms of SiO 2 .
ＣａはＳｉと同様に粒界に偏析し、粒界抵抗を高め、渦電流損失を低減させ、もって高周波数領域における磁心損失を低減させる効果を有する。量が少なすぎると粒界抵抗を高める効果が少なく、量が多すぎると逆に結晶の肥大化を誘発し磁心損失を劣化させる。Ｃａ含有量が、前記酸化物換算での前記主成分の合計１００質量部に対してＣａＣＯ３換算で０．０６〜０．３質量部であれば渦電流損失を低減するのに十分な粒界抵抗を確保でき、１ＭＨｚ以上の高周波領域で低損失とすることができる。Ｃａ含有量は、更に好ましくはＣａＣＯ３換算で０．０６〜０．２質量部である。 Like Si, Ca segregates at the grain boundaries, increases grain boundary resistance, reduces eddy current loss, and thus has the effect of reducing magnetic core loss in the high frequency region. If the amount is too small, the effect of increasing the grain boundary resistance is small, and if the amount is too large, on the contrary, the crystal enlargement is induced and the magnetic core loss is deteriorated. If the Ca content is 0.06 to 0.3 parts by mass in terms of CaCO 3 with respect to 100 parts by mass of the total of the main components in terms of oxides, the grain boundaries are sufficient to reduce the eddy current loss. Resistance can be secured and low loss can be achieved in a high frequency region of 1 MHz or more. The Ca content is more preferably 0.06 to 0.2 parts by mass in terms of CaCO 3 .
副成分として更に５ａ族金属のＶ、Ｎｂ又Ｔａを含んでも良い（５ａ族金属とはＶ、Ｎｂ及びＴａからなる群から選ばれた少なくとも一種であり、以下総称して５ａ族と呼ぶ）。５ａ族金属はＳｉ及びＣａとともに粒界に主に酸化物として偏析し、粒界相をより高抵抗化することにより、磁心損失を更に低減させる効果を有する。 As a subcomponent, V, Nb or Ta of the group 5a metal may be further contained (the group 5a metal is at least one selected from the group consisting of V, Nb and Ta, and is hereinafter collectively referred to as group 5a). The group 5a metal segregates mainly as an oxide at the grain boundaries together with Si and Ca, and has an effect of further reducing the magnetic core loss by increasing the resistance of the grain boundary phase.
ＶはＮｂ及びＴａより低融点で、結晶粒の成長を促進する機能も有する。Ｖは、他の５ａ族に比べ低融点であることから粒界との濡れ性が良いと考えられ、焼結体の加工性を向上し、欠け等の発生を抑制する効果も有する。Ｖは量が多すぎると結晶の肥大化を誘発し磁心損失を劣化させる。Ｖ含有量が、前記酸化物換算での前記主成分の合計１００質量部に対してＶ２Ｏ５換算で０〜０．１質量部であれば渦電流損失を低減するに十分な粒界抵抗を確保でき、１ＭＨｚ以上の高周波数領域で低損失とすることができる。Ｖ含有量は、更に好ましくはＶ２Ｏ５換算で０〜０．０５質量部である。 V has a melting point lower than that of Nb and Ta, and also has a function of promoting the growth of crystal grains. Since V has a lower melting point than the other 5a groups, it is considered that it has good wettability with grain boundaries, and has the effect of improving the processability of the sintered body and suppressing the occurrence of chips and the like. If the amount of V is too large, it induces crystal enlargement and deteriorates magnetic core loss. If the V content is 0 to 0.1 parts by mass in terms of V 2 O 5 with respect to 100 parts by mass of the total of the main components in terms of oxide, sufficient grain boundary resistance to reduce eddy current loss. Can be secured, and low loss can be achieved in a high frequency region of 1 MHz or higher. The V content is more preferably 0 to 0.05 parts by mass in terms of V 2 O 5 .
Ｎｂ及び／又はＴａは、結晶粒の成長を抑制し均一な結晶組織とし、磁心損失を低減する効果も有する。Ｎｂ及びＴａはＶより高融点であり、Ｃａ及びＳｉとともにＦｅとの酸化物による低融点化を阻止する効果も有する。Ｎｂ及びＴａは、量が多すぎると粒内に偏析し磁心損失を劣化させる。前記酸化物換算での前記主成分の合計１００質量部に対してＮｂ（Ｎｂ２Ｏ５換算）及びＴａ（Ｔａ２Ｏ５換算）の総量が０〜０．３質量部であれば渦電流損失を低減するのに十分な粒界抵抗を確保でき、１ＭＨｚ以上の高周波数領域で低損失とすることができる。更に、Ｎｂ及びＴａは熱処理後における磁心損失のうち、特に高温（１００℃）でのヒステリシス損失、残留損失を低減する効果を有し、高周波領域で広い温度範囲での低損失化を実現するのに有効である。Ｎｂ（Ｎｂ２Ｏ５換算）及びＴａ（Ｔａ２Ｏ５換算の総量は、更に好ましくは０〜０．２質量部である。 Nb and / or Ta also have the effect of suppressing the growth of crystal grains to form a uniform crystal structure and reducing magnetic core loss. Nb and Ta have higher melting points than V, and have the effect of preventing the melting point of Nb and Ta from being lowered by oxides with Fe together with Ca and Si. If the amounts of Nb and Ta are too large, they segregate into the grains and deteriorate the magnetic core loss. Eddy current loss if the total amount of Nb (Nb 2 O 5 conversion) and Ta (Ta 2 O 5 conversion) is 0 to 0.3 parts by mass with respect to the total 100 parts by mass of the main component in terms of oxide. Sufficient grain boundary resistance can be secured, and low loss can be achieved in a high frequency region of 1 MHz or more. Further, Nb and Ta have the effect of reducing the hysteresis loss and the residual loss at a particularly high temperature (100 ° C.) among the magnetic core losses after the heat treatment, and realize the reduction in a wide temperature range in a high frequency region. It is effective for. The total amount of Nb (converted to Nb 2 O 5 ) and Ta (converted to Ta 2 O 5 ) is more preferably 0 to 0.2 parts by mass.
Ｔａ含有量はＴａ２Ｏ５換算で０〜０．１質量部であるのが好ましく、０〜０．０５質量部であるのがより好ましい。Ｎｂ含有量は、Ｎｂ２Ｏ５換算で０．０５質量部以下（０は含まない）であるのが好ましく、０．０１〜０．０４質量部であるのがより好ましい。 The Ta content is preferably 0 to 0.1 parts by mass, more preferably 0 to 0.05 parts by mass in terms of Ta 2 O 5 . The Nb content is preferably 0.05 parts by mass or less (not including 0) in terms of Nb 2 O 5 , and more preferably 0.01 to 0.04 parts by mass.
本実施形態のＭｎＺｎ系フェライトは、２〜５μｍの平均結晶粒径を有するのが好ましい。平均結晶粒径が５μｍ以下であれば、渦電流損失が低減し、かつ磁壁の減少から残留損失が低減し、高周波数領域での磁心損失が低下する。しかし、平均結晶粒径が２μｍ未満であると、粒界が磁壁のピンニング点として作用し、また反磁界の影響から、透磁率の低下及び磁心損失の増加を誘発する傾向となる。平均結晶粒径が５μｍを超えると、渦電流損失の増加により１ＭＨｚ以上の高周波数領域における磁心損失が増加する傾向となる。
なお、平均結晶粒径はＭｎＺｎ系フェライトの焼結体の断面を鏡面研磨し、サーマルエッチング（９５０〜１０５０℃で１時間、Ｎ２中で処理）し、その断面を光学顕微鏡又は走査型電子顕微鏡で２０００倍にて写真撮影し、この写真上の６０μｍ×４０μｍの長方形領域を基準に求積法（ＪＩＳ Ｈ０５０１−１９８６相当）により算出することができる。結晶粒径の大きさによって十分な粒子数（３００個以上）がカウントできない場合は、観察される粒子数が３００個以上となるよう観察領域を適宜調整することができる。
The MnZn-based ferrite of the present embodiment preferably has an average crystal grain size of 2 to 5 μm. When the average crystal grain size is 5 μm or less, the eddy current loss is reduced, the residual loss is reduced due to the reduction of the domain wall, and the magnetic core loss in the high frequency region is reduced. However, when the average crystal grain size is less than 2 μm, the grain boundaries act as pinning points of the domain wall, and the influence of the demagnetic field tends to induce a decrease in magnetic permeability and an increase in magnetic core loss. When the average crystal grain size exceeds 5 μm, the magnetic core loss tends to increase in the high frequency region of 1 MHz or more due to the increase in the eddy current loss.
The average crystal grain size is mirror-polished cross-section of the sintered body of MnZn ferrite, (1 hour at 950 to 1050 ° C., treated in N 2) thermal etching, optical microscopy or scanning electron microscope cross-section It can be calculated by the calcination method (corresponding to JIS H0501-1986) based on the rectangular region of 60 μm × 40 μm on the photograph taken at 2000 times. When a sufficient number of particles (300 or more) cannot be counted due to the size of the crystal grain size, the observation region can be appropriately adjusted so that the number of observed particles is 300 or more.
［２］製造方法
（１）成形工程
ＭｎＺｎ系フェライトの原料粉末としては、主成分の原料としてＦｅ２Ｏ３、Ｍｎ３Ｏ４及びＺｎＯの粉末を使用し、副成分の原料としてＣｏ３Ｏ４、ＳｉＯ２、ＣａＣＯ３等の粉末を使用する。焼結工程に供する成形体は、主成分の原料を仮焼成した仮焼粉に、副成分の原料を投入し、所定の平均粒径となるまで粉砕及び混合し、得られた混合物にバインダとして例えばポリビニルアルコールを加えて得られる造粒粉を用いて形成される。なおＣｏ３Ｏ４は主成分の原料とともに仮焼成前に加えても良い。バインダは有機物であって昇温工程にてほぼ分解するが、条件によっては焼結後にカーボンが残留して磁気特性を劣化させる場合があり、低酸素濃度雰囲気への切り替えのタイミングは、バインダが十分に分解するように適宜調整するのが望ましい。
成形体の形状としては、例えば、１００ｍｍ×１００ｍｍ×３ｍｍの平板状とすることができる。焼結後に粉砕されるため、粉砕工程にて都合の良い形状とすればよい。平板状としては、特に限定するものではないが１辺が１０ｍｍ〜１００ｍｍ程度の矩形状で、厚さが１ｍｍ〜５ｍｍ程度の平板状とすることが好ましい。
[2] Manufacturing method (1) Molding process As the raw material powder for MnZn-based ferrite, powders of Fe 2 O 3 , Mn 3 O 4 and Zn O are used as the raw materials for the main component, and Co 3 O 4 is used as the raw material for the auxiliary components. , SiO 2 , CaCO 3, etc. are used. The molded product to be used in the sintering step is prepared by adding the raw material of the sub-component to the calcined powder obtained by calcining the raw material of the main component, crushing and mixing until the particle size reaches a predetermined average, and then using the obtained mixture as a binder. For example, it is formed by using a granulated powder obtained by adding polyvinyl alcohol. In addition, Co 3 O 4 may be added together with the raw material of the main component before the preliminary firing. The binder is an organic substance and is almost decomposed in the temperature raising process, but depending on the conditions, carbon may remain after sintering and deteriorate the magnetic characteristics, so the binder is sufficient for the timing of switching to the low oxygen concentration atmosphere. It is desirable to adjust appropriately so that it decomposes into.
The shape of the molded body can be, for example, a flat plate of 100 mm × 100 mm × 3 mm. Since it is crushed after sintering, it may be formed into a shape that is convenient in the crushing process. The flat plate shape is not particularly limited, but is preferably a flat plate shape having a side of about 10 mm to 100 mm and a thickness of about 1 mm to 5 mm.
（２）焼結工程
ＭｎＺｎ系フェライトの原料粉末の成形体を焼結することによって、ＭｎＺｎ系フェライトの焼結体を得る。前記焼結は、昇温工程と、高温保持工程と、降温工程とを有する。前記高温保持工程において、保持温度は１０５０℃超１１５０℃未満とするのが好ましく、雰囲気中の酸素濃度を０．４〜２体積％とするのが好ましい。降温工程において少なくとも（Ｔｃ＋７０）℃から１００℃までの間の降温速度は５０℃／時間以上とするのが好ましく、更に前記保持温度から１００℃までの間の降温速度は、５０℃／時間以上とするのが好ましい。
(2) Sintering Step A sintered body of MnZn-based ferrite is obtained by sintering a molded body of a raw material powder of MnZn-based ferrite. The sintering has a temperature raising step, a high temperature holding step, and a temperature lowering step. In the high temperature holding step, the holding temperature is preferably more than 1050 ° C and less than 1150 ° C, and the oxygen concentration in the atmosphere is preferably 0.4 to 2% by volume. In the temperature lowering step, the temperature lowering rate from at least (Tc + 70) ° C. to 100 ° C. is preferably 50 ° C./hour or more, and the temperature lowering rate from the holding temperature to 100 ° C. is 50 ° C./hour or more. It is preferable to do so.
（ａ）昇温工程
昇温工程においては、少なくとも９００℃以上で、雰囲気中の酸素濃度を０．４〜２体積％の範囲とするのが好ましい。フェライトの生成が開始される９００℃以上の温度で酸素濃度を制御する事で、より緻密で高密度の焼結体を得る事ができる。
(A) Temperature rise step In the temperature rise step, it is preferable that the oxygen concentration in the atmosphere is in the range of 0.4 to 2% by volume at at least 900 ° C. or higher. By controlling the oxygen concentration at a temperature of 900 ° C. or higher at which the formation of ferrite is started, a denser and higher density sintered body can be obtained.
（ｂ）高温保持工程
高温保持工程における保持温度が１０５０℃以下であると十分な焼結密度が得られず、微細な結晶と空孔を多く含む組織となり易い。保持温度が１１５０℃以上であると、焼結は促進されるが、得られる結晶粒は相対的に大きな粒径となり易く、その結果、渦電流損失が増加する傾向がある。そのため、高温保持工程における保持温度が前記規定から外れると磁心損失が大きくなる傾向にある。高温保持工程における保持温度を１１５０℃未満として低温化する事で、結晶の肥大化を抑制することが可能となり、渦電流損失の増加をより抑制することができる。本発明において、高温保持工程における保持温度は、好ましくは１０６０〜１１４０℃であり、更に好ましくは１０７０〜１１３０℃である。
(B) High temperature holding step If the holding temperature in the high temperature holding step is 1050 ° C. or lower, a sufficient sintering density cannot be obtained, and a structure containing many fine crystals and pores tends to be formed. When the holding temperature is 1150 ° C. or higher, sintering is promoted, but the obtained crystal grains tend to have a relatively large particle size, and as a result, the eddy current loss tends to increase. Therefore, if the holding temperature in the high temperature holding step deviates from the above specification, the magnetic core loss tends to increase. By lowering the holding temperature in the high temperature holding step to less than 1150 ° C., it is possible to suppress the enlargement of crystals and further suppress the increase in eddy current loss. In the present invention, the holding temperature in the high temperature holding step is preferably 106 to 1140 ° C, more preferably 1070 to 1130 ° C.
高温保持工程における酸素濃度が０．４体積％未満では、雰囲気が還元的となり、焼結して得られるＭｎＺｎ系フェライトが低抵抗化して渦電流損失が増加する。一方、酸素濃度が２体積％超では、雰囲気が酸化的になりすぎるため、低抵抗のヘマタイトが生成され易くなり、かつ得られる結晶粒の粒径が相対的に大きくなり、部分的に結晶の肥大化を起こし易い。そのため、渦電流損失が増加し、高周波数、高励磁磁束密度で、低温から高温に至る全温度領域（０〜１２０℃）において磁心損失が大きくなる傾向となる。 If the oxygen concentration in the high temperature holding step is less than 0.4% by volume, the atmosphere becomes reducing, the MnZn-based ferrite obtained by sintering becomes low in resistance, and the eddy current loss increases. On the other hand, when the oxygen concentration exceeds 2% by volume, the atmosphere becomes too oxidative, so that low-resistance hematite is likely to be generated, and the grain size of the obtained crystal grains becomes relatively large, so that the crystals are partially formed. Prone to bloat. Therefore, the eddy current loss increases, and the magnetic core loss tends to increase in the entire temperature range (0 to 120 ° C.) from low temperature to high temperature at high frequency and high exciting magnetic flux density.
酸素濃度は保持温度に応じて設定するのが好ましく、保持温度が高いほど相対的に酸素濃度を高く設定する。保持温度に応じた酸素濃度の設定によってＣａが結晶粒界に偏析して粒界が高抵抗化して磁心損失を低減する事ができる。 The oxygen concentration is preferably set according to the holding temperature, and the higher the holding temperature, the higher the oxygen concentration is set. By setting the oxygen concentration according to the holding temperature, Ca segregates at the grain boundaries, the grain boundaries become high resistance, and the magnetic core loss can be reduced.
酸素濃度が低いほど正の結晶磁気異方性定数を有するＦｅ２＋量が増加し、磁心損失の極小となる温度が低くなる傾向にあるので、酸素濃度は前記範囲から外れないように設定するのが好ましい。 The lower the oxygen concentration, the higher the amount of Fe 2+ having a positive magnetocrystalline anisotropy constant, and the temperature at which the magnetic core loss is minimized tends to decrease. Therefore, the oxygen concentration is set so as not to deviate from the above range. Is preferable.
（ｃ）降温工程
高温保持工程の後に続く降温工程では、まず高温保持工程の雰囲気から酸素濃度を低下させ、過度の酸化及び過度の還元を防ぐような酸素濃度に設定する。９００℃から４００℃の温度範囲で、雰囲気の酸素濃度を０．００１〜０．２体積％とすることによりＦｅ２＋生成量を好ましい範囲で調整できる。ここで、高温保持工程の後に続く降温工程において、雰囲気を所定の酸素濃度に調整する９００℃から４００℃までの間を第１降温工程と呼ぶ。
(C) Temperature lowering step In the temperature lowering step following the high temperature holding step, the oxygen concentration is first lowered from the atmosphere of the high temperature holding step, and the oxygen concentration is set so as to prevent excessive oxidation and excessive reduction. By setting the oxygen concentration in the atmosphere to 0.001 to 0.2% by volume in the temperature range of 900 ° C. to 400 ° C., the amount of Fe 2+ produced can be adjusted in a preferable range. Here, in the temperature lowering step following the high temperature holding step, the range from 900 ° C. to 400 ° C. for adjusting the atmosphere to a predetermined oxygen concentration is referred to as a first temperature lowering step.
高温保持工程から続いて、降温工程においても酸素濃度を制御し前記範囲に調整することにより、ＭｎＺｎ系フェライトの粒界にＣａを偏析させるとともに、結晶粒内に固溶するＣａ量を適宜制御して、結晶粒内と粒界の抵抗を高めて渦電流損失に係る磁心損失を低減することができる。 By controlling the oxygen concentration in the temperature lowering step following the high temperature holding step and adjusting it to the above range, Ca is segregated at the grain boundaries of MnZn-based ferrite, and the amount of Ca dissolved in the crystal grains is appropriately controlled. Therefore, it is possible to increase the resistance between the crystal grains and the grain boundaries and reduce the magnetic core loss related to the eddy current loss.
第１降温工程での降温速度は、焼結炉内の温度及び酸素濃度の調整が可能な範囲であれ
ば特に限定されないが、５０〜３００℃／時間とするのが好ましい。第１降温工程での降温速度が５０℃／時間未満であると焼結工程に時間を要し、焼結炉内に滞留する時間が長くなり、生産性が低下してコストの上昇を招くので好ましくない。一方、降温速度が３００℃／時間超であると、焼結炉の能力にもよるが焼結炉内の温度や酸素濃度の均一性を保つのが困難な場合がある。
The temperature lowering rate in the first temperature lowering step is not particularly limited as long as the temperature and oxygen concentration in the sintering furnace can be adjusted, but it is preferably 50 to 300 ° C./hour. If the temperature lowering rate in the first temperature lowering step is less than 50 ° C./hour, the sintering step takes time, the time remaining in the sintering furnace becomes longer, the productivity decreases, and the cost increases. Not preferable. On the other hand, if the temperature lowering rate exceeds 300 ° C./hour, it may be difficult to maintain the uniformity of the temperature and oxygen concentration in the sintering furnace, depending on the capacity of the sintering furnace.
高温保持工程における保持温度と酸素濃度とを所定の範囲とし、第１降温工程において９００℃から４００℃まで降温させる際の酸素濃度を特定の範囲で制御する事で、結晶粒径のばらつきを抑え、Ｃｏ２＋イオン及びＦｅ２＋イオンを適正な量に制御し磁心損失を低減することができる。 By setting the holding temperature and oxygen concentration in the high temperature holding step within a predetermined range and controlling the oxygen concentration when lowering the temperature from 900 ° C. to 400 ° C. in the first temperature lowering step within a specific range, variation in crystal particle size is suppressed. , Co 2+ ions and Fe 2+ ions can be controlled to an appropriate amount to reduce the magnetic core loss.
降温工程では、ＭｎＺｎ系フェライトの主成分を構成する酸化鉄（Ｆｅ２Ｏ３）と酸化亜鉛（ＺｎＯ）とのモル％から計算により求められるキュリー温度をＴｃ（℃）としたとき、（Ｔｃ＋７０）℃から１００℃までの間の降温速度を５０℃／時間〜３００℃／時間とするのが好ましい。典型的には４００℃から１００℃まで間の降温速度を５０℃／時間〜３００℃／時間とするのが望ましい。ここで降温工程においてＴｃを含む（Ｔｃ＋７０）℃から１００℃までの温度範囲を所定の降温速度で降温する間を第２降温工程と呼ぶ。 In the temperature lowering step, when the Curie temperature calculated from the molar% of iron oxide (Fe 2 O 3 ) and zinc oxide (Zn O) constituting the main component of MnZn-based ferrite is Tc (° C.), (Tc + 70). The temperature lowering rate between ° C. and 100 ° C. is preferably 50 ° C./hour to 300 ° C./hour. Typically, it is desirable that the temperature lowering rate between 400 ° C. and 100 ° C. is 50 ° C./hour to 300 ° C./hour. Here, in the temperature lowering step, the period during which the temperature range from (Tc + 70) ° C. to 100 ° C. including Tc is lowered at a predetermined lowering rate is referred to as a second temperature lowering step.
第２降温工程での降温速度を５０℃／時間未満とすると、Ｃｏ２＋及びＦｅ２＋に起因する誘導磁気異方性の影響を受け易く高温側の磁心損失が劣化する場合があり望ましくない。一方、降温速度が３００℃／時間超であると、焼結炉の能力にもよるが、焼結炉内の温度や降温速度を調整するのが困難な場合がある。 If the temperature lowering rate in the second temperature lowering step is less than 50 ° C./hour, it is easily affected by the induced magnetic anisotropy caused by Co 2+ and Fe 2+ , and the magnetic core loss on the high temperature side may deteriorate, which is not desirable. On the other hand, if the temperature lowering rate exceeds 300 ° C./hour, it may be difficult to adjust the temperature and the temperature lowering rate in the sintering furnace, depending on the capacity of the sintering furnace.
第２降温工程における雰囲気は、不活性ガス雰囲気でも良いし大気雰囲気でも構わない。第１降温工程の酸素濃度を制御した雰囲気のまま、又は第２降温工程の途中で大気雰囲気や不活性ガス雰囲気にしても構わない。 The atmosphere in the second temperature lowering step may be an inert gas atmosphere or an atmospheric atmosphere. The atmosphere in which the oxygen concentration in the first temperature lowering step is controlled may be maintained, or the atmosphere may be an atmospheric atmosphere or an inert gas atmosphere in the middle of the second temperature lowering step.
（３）粉砕工程
ＭｎＺｎ系フェライトの焼結体を粉砕してＭｎＺｎ系フェライト粉を得る。
粉砕工程では、粗粉砕工程と微粉砕工程とに分けて行うことが好ましい。粗粉砕と微粉砕との間に中粉砕工程を設けてもよい。粉砕の工程数は適宜選択できる。
(3) Crushing Step The sintered body of MnZn-based ferrite is crushed to obtain MnZn-based ferrite powder.
The pulverization step is preferably divided into a coarse pulverization step and a fine pulverization step. A medium pulverization step may be provided between the coarse pulverization and the fine pulverization. The number of crushing steps can be appropriately selected.
本実施形態において、粗粉砕工程は、大きさが数ｍｍ角程度の粗粉砕粉となるように行うことが好ましい。例えば、固定式と揺動式２枚の板状粉砕歯を有し、入口と出口で角度を設けて出口側を狭め粉砕された粗粉砕粉を隙間から排出する構造を有する連続式ジョークラッシャーを用いることができる。粒度調整は出口間隔の設定幅を調整することにより行うことができる。 In the present embodiment, the coarse pulverization step is preferably performed so that the coarse pulverized powder has a size of about several mm square. For example, a continuous jaw crusher having two plate-shaped crushed teeth, a fixed type and a swing type, and having a structure in which an angle is provided at the inlet and the outlet to narrow the outlet side and crushed coarse crushed powder is discharged from a gap. Can be used. The particle size adjustment can be performed by adjusting the set width of the outlet interval.
この粗粉砕工程で得られた粗粉砕粉は、例えば、目開き１．５ｍｍの篩を用いて分級し、篩を通過した粗粉砕粉を微粉砕工程に送ることができる。篩に残った粗粉砕粉は、再度粗粉砕工程に戻し、所望の大きさとなるまで粗粉砕すればよい。なお、ここで用いる篩は、目開き３ｍｍ以下とすることが好ましい。更に２ｍｍ以下が好ましい。また、この篩を用いた分級は、振動篩機を用いることができる。 The coarsely pulverized powder obtained in this coarse pulverization step can be classified using, for example, a sieve having a mesh size of 1.5 mm, and the coarsely pulverized powder that has passed through the sieve can be sent to the fine pulverization step. The coarsely pulverized powder remaining on the sieve may be returned to the coarse pulverization step again and coarsely pulverized to a desired size. The sieve used here preferably has a mesh opening of 3 mm or less. Further, it is preferably 2 mm or less. Further, a vibrating sieve can be used for classification using this sieve.
微粉砕工程では、粗粉砕粉を微粉砕して、おおむね１００μｍ以下の微粉砕粉を得る。
この微粉砕工程では、例えば、振動式ミルを用いることができる。振動式ミルには連続式とバッチ式があり、粉砕ドラム中に粉砕用のメディア（球状や棒状のもの）を配置し、処理物とメディアを激しく振動させることで粉砕する機構となっている。粒度はメディア量やその形態、処理物の投入量、処理時間、振幅量等で調整できる。
In the fine pulverization step, the coarsely pulverized powder is pulverized to obtain a finely pulverized powder having a size of about 100 μm or less.
In this pulverization step, for example, a vibrating mill can be used. There are two types of vibrating mills, continuous type and batch type. A crushing medium (spherical or rod-shaped) is placed in a crushing drum, and the processed material and the media are vibrated violently to crush. The particle size can be adjusted by adjusting the amount of media, its form, the amount of processed material charged, the processing time, the amount of amplitude, and the like.
この微粉砕工程で得られた微粉砕粉は、例えば、目開き１９８μｍの篩を用いて分級し、篩を通過した微粉砕粉を粉砕工程後のＭｎＺｎ系フェライト粉として用いることができる。篩に残ったＭｎＺｎ系フェライトの粉砕粉は、再度微粉砕工程に戻し、所望の大きさとなるまで微粉砕すればよい。なお、ここで用いる篩の目開き上限値は目的の粒度にあわせ、例えば汎用で用いられる３０μｍ〜２００μｍ程度の目開きを有する篩を適宜選択し調整すればよい。また、この篩を用いた分級は、振動篩機を用いることができる。この篩はＭｎＺｎ系フェライト粉の粒径の上限を決めるものであるが、微細過ぎる粉砕粉を除くために、粒径の下限を決める篩を行ってもよい。 The finely pulverized powder obtained in this fine pulverization step can be classified using, for example, a sieve having an opening of 198 μm, and the finely pulverized powder that has passed through the sieve can be used as the MnZn-based ferrite powder after the pulverization step. The pulverized powder of MnZn-based ferrite remaining on the sieve may be returned to the pulverization step again and pulverized until the desired size is obtained. The upper limit of the mesh size of the sieve used here may be adjusted by appropriately selecting a sieve having a mesh size of about 30 μm to 200 μm, which is used for general purposes, according to the target particle size. Further, a vibrating sieve can be used for classification using this sieve. This sieve determines the upper limit of the particle size of the MnZn-based ferrite powder, but in order to remove the pulverized powder that is too fine, a sieve that determines the lower limit of the particle size may be performed.
（４）熱処理工程
本実施形態では、ＭｎＺｎ系フェライトの焼結体を粉砕する前に熱処理する熱処理工程と、ＭｎＺｎ系フェライトの焼結体を粉砕したＭｎＺｎ系フェライト粉を熱処理する熱処理工程とのうち、少なくとも一方の熱処理工程を備える。なお、両方の熱処理工程を行ってもよい。
この熱処理工程は、
条件１：２００℃以上、及び
条件２：（Ｔｃ−９０）℃〜（Ｔｃ＋１００）℃［ただし、Ｔｃは前記ＭｎＺｎ系フェライトの主成分に含まれるＦｅ２Ｏ３及びＺｎＯのモル％から計算により求められるキュリー温度（℃）である。］
を満たす温度まで加熱し、一定時間保持した後、前記保持温度から５０℃／時間以下の速度で降温する熱処理工程である。
前記保持温度が、２００℃未満又は（Ｔｃ−９０）℃未満であると、ＭｎＺｎ系フェライトの磁心損失の低減効果が得られ難くなる。また（Ｔｃ＋１００）℃超であると磁心損失の低減効果が上限に達する。前記保持温度からの降温速度が５０℃／時間超であると、磁心損失の低減効果が十分に発揮されなくなる。なお、降温速度は保持温度から１５０℃までの温度範囲で算出する。
(4) Heat Treatment Step In the present embodiment, of the heat treatment step of heat-treating the sintered body of MnZn-based ferrite before crushing and the heat treatment step of heat-treating the MnZn-based ferrite powder obtained by crushing the sintered body of MnZn-based ferrite. , At least one heat treatment step is provided. Both heat treatment steps may be performed.
This heat treatment process
Condition 1: 200 ° C. or higher, and Condition 2: (Tc-90) ° C. to (Tc + 100) ° C. [However, Tc is the Curie temperature calculated from the molar% of Fe2O3 and ZnO contained in the main components of the MnZn-based ferrite. (° C). ]
This is a heat treatment step in which the temperature is heated to a temperature that satisfies the above conditions, held for a certain period of time, and then lowered from the holding temperature at a rate of 50 ° C./hour or less.
If the holding temperature is less than 200 ° C. or less than (Tc-90) ° C., it becomes difficult to obtain the effect of reducing the magnetic core loss of MnZn-based ferrite. Further, when the temperature exceeds (Tc + 100) ° C., the effect of reducing the magnetic core loss reaches the upper limit. If the temperature lowering rate from the holding temperature exceeds 50 ° C./hour, the effect of reducing the magnetic core loss is not sufficiently exhibited. The temperature lowering rate is calculated in the temperature range from the holding temperature to 150 ° C.
前記熱処理は大気中で行なっても良いし、還元雰囲気中で行なっても良い。大気中など酸化雰囲気である場合には、ＭｎＺｎ系フェライトの酸化による磁気特性劣化を防ぐように、熱処理はその温度の上限を４００℃以下とするのが好ましく、降温速度が５℃／時間程度と遅い場合は３５０℃未満とするのが好ましい。また還元雰囲気であれば、熱処理の温度の上限は酸化によって限定されないが、磁心損失の低減効果が上限に達することを考慮すれば、酸化雰囲気での熱処理と同様に４００℃以下とするのが好ましい。 The heat treatment may be carried out in the atmosphere or in a reducing atmosphere. In the case of an oxidizing atmosphere such as in the atmosphere, the upper limit of the temperature of the heat treatment is preferably 400 ° C. or less, and the temperature lowering rate is about 5 ° C./hour so as to prevent deterioration of magnetic properties due to oxidation of MnZn-based ferrite. If it is slow, it is preferably less than 350 ° C. Further, in the case of a reducing atmosphere, the upper limit of the heat treatment temperature is not limited by oxidation, but considering that the effect of reducing magnetic core loss reaches the upper limit, it is preferably 400 ° C. or lower as in the heat treatment in an oxidizing atmosphere. ..
熱処理における昇温速度は特に限定するものではないが、装置の性能や熱応力による歪の影響を受けない程度に適宜選定すれば良く、典型的には１００℃〜３００℃／時間とすれば良い。 The rate of temperature rise in the heat treatment is not particularly limited, but it may be appropriately selected so as not to be affected by the performance of the apparatus and strain due to thermal stress, and typically 100 ° C. to 300 ° C./hour. ..
熱処理における保持時間は特に限定するものではないが、装置内に配置した試料が所定の温度に至るに必要な時間を設ければ良く、典型的には１時間程度とすれば良い。
本発明の熱処理は熱処理炉（電気炉、恒温槽等）を用いて行うことができる。
The holding time in the heat treatment is not particularly limited, but the time required for the sample placed in the apparatus to reach a predetermined temperature may be provided, and typically it may be about 1 hour.
The heat treatment of the present invention can be carried out using a heat treatment furnace (electric furnace, constant temperature bath, etc.).
本実施形態のＭｎＺｎ系フェライト粉は、粒径が１μｍ以下のものは少ない方が良い。過粉砕となると焼結体を構成する結晶が破壊され、粉砕粉の平均粒径が小さくなるに従い特性が劣化する傾向にある。ＭｎＺｎ系フェライト粉は、粒径１μｍの通過分積算（％）が１５％以下となる粒度分布を備えることが好ましい。更に好ましくは１０％以下であり、分級により０％としても良い。このＭｎＺｎ系フェライトの平均結晶粒径が約２〜５μｍであるので、１μｍ以下のものは、特性への寄与が低く、その含有量は少ない方が好ましい。
また、このＭｎＺｎ系フェライト粉は、樹脂等と混ぜられ、磁心等の形態に成形されて使用されることが考えられる。このとき、粒径が大きいと、均一な混錬や充填密度が上がらない。そのため、平均粒径Ｄ５０は１００μｍ以下であることが好ましい。
本実施形態のＭｎＺｎ系フェライト粉は、平均粒径Ｄ５０が１μｍ以上であることが好ましく、更に好ましくは５μｍ以上であり、１０μｍ以上であるのがいっそう好ましい。また、１００μｍ以下であるのが好ましく、更に好ましくは９０μｍ以下であり、８０μｍ以下であるのがいっそう好ましい。
The MnZn-based ferrite powder of the present embodiment preferably has a particle size of 1 μm or less. When over-pulverized, the crystals constituting the sintered body are destroyed, and the characteristics tend to deteriorate as the average particle size of the pulverized powder decreases. The MnZn-based ferrite powder preferably has a particle size distribution in which the cumulative (%) of passages having a particle size of 1 μm is 15% or less. More preferably, it is 10% or less, and may be 0% depending on the classification. Since the average crystal grain size of this MnZn-based ferrite is about 2 to 5 μm, those having a diameter of 1 μm or less have a low contribution to the characteristics, and it is preferable that the content thereof is small.
Further, it is conceivable that this MnZn-based ferrite powder is mixed with a resin or the like and molded into a form such as a magnetic core before use. At this time, if the particle size is large, uniform kneading and filling density do not increase. Therefore, the average particle size D50 is preferably 100 μm or less.
The MnZn-based ferrite powder of the present embodiment preferably has an average particle size D50 of 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. Further, it is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less.
表１に示す組成となるようにＭｎＺｎ系フェライトの原料粉末を準備した。主成分の原料には、Ｆｅ２Ｏ３、Ｍｎ３Ｏ４（ＭｎＯ換算）及びＺｎＯを用い、これらを湿式混合した後乾燥させ、９００℃で１．５時間仮焼成した。次いで、ボールミルに仮焼成粉１００質量部に対して、Ｃｏ３Ｏ４、ＳｉＯ２、ＣａＣＯ３、Ｖ２Ｏ５、Ｔａ２Ｏ５及びＮｂ２Ｏ５を表１に示すように加えて、平均粉砕粒径（空気透過法）が０．８〜１．０μｍとなるまで粉砕・混合した。得られた混合物にバインダとしてポリビニルアルコールを加え、スプレードライヤーにて顆粒化した後、１９６ＭＰａで加圧成形して平板状の成形体（１００ｍｍ×１００ｍｍ×３ｍｍ）を得た。得られた成形体を雰囲気調整が可能な電気焼結炉にて焼結して、平板状の焼結体を得た。その平均結晶粒径は３μｍであった。 A raw material powder of MnZn-based ferrite was prepared so as to have the composition shown in Table 1. Fe 2 O 3 , Mn 3 O 4 (MnO conversion) and ZnO were used as the raw materials of the main component, and these were wet-mixed, dried, and calcined at 900 ° C. for 1.5 hours. Next, Co 3 O 4 , SiO 2 , CaCO 3 , V 2 O 5 , Ta 2 O 5 and Nb 2 O 5 were added to the ball mill with respect to 100 parts by mass of the calcined powder as shown in Table 1 and averaged. The mixture was pulverized and mixed until the pulverized particle size (air permeation method) became 0.8 to 1.0 μm. Polyvinyl alcohol was added as a binder to the obtained mixture, granulated by a spray dryer, and then pressure-molded at 196 MPa to obtain a flat molded body (100 mm × 100 mm × 3 mm). The obtained molded product was sintered in an electric sintering furnace capable of adjusting the atmosphere to obtain a flat plate-shaped sintered body. The average crystal grain size was 3 μm.
焼結は、室温から７５０℃に至る間の昇温工程においては大気中で行い、７５０℃にてＮ２ガスでの置換を開始して酸素濃度を徐々に低下させ９００℃で酸素濃度を０．６５体積％にし、１１１５℃に設定された高温保持工程の温度まで、昇温速度１３０℃／時間で昇温した。高温保持工程では酸素濃度を０．６５体積％とし、４時間保持した。降温工程では、１０００℃から８５０℃まで酸素濃度を徐々に低下させ、１０００℃で０．６５体積％、９００℃で０．０５体積％、８５０℃以下で０．００５体積％となるように調整した。降温工程では１５０℃／時間の降温速度で１００℃まで降温した後、電気焼結炉から平板状の焼結体を取り出した。なお酸素濃度はジルコニア式酸素分析装置で測定し、温度は焼結炉に設けられた熱電対にて測温した。 Sintering is carried out in the atmosphere in the heating process between reaching the 750 ° C. from room temperature, 0 oxygen concentration gradually 900 ° C. to reduce the oxygen concentration to start substitution with N 2 gas at 750 ° C. The temperature was raised to .65% by volume at a heating rate of 130 ° C./hour to the temperature of the high temperature holding step set at 1115 ° C. In the high temperature holding step, the oxygen concentration was set to 0.65% by volume and held for 4 hours. In the temperature lowering step, the oxygen concentration is gradually lowered from 1000 ° C. to 850 ° C. and adjusted to 0.65% by volume at 1000 ° C., 0.05% by volume at 900 ° C., and 0.005% by volume at 850 ° C. or lower. did. In the temperature lowering step, the temperature was lowered to 100 ° C. at a temperature lowering rate of 150 ° C./hour, and then the flat plate-shaped sintered body was taken out from the electric sintering furnace. The oxygen concentration was measured with a zirconia oxygen analyzer, and the temperature was measured with a thermocouple provided in the sintering furnace.
（キュリー温度）
フェライト（丸善株式会社、昭和６１年１１月３０日発行、第６刷、７９頁）に記載の式：
Ｔｃ＝１２．８×［ｙ−（２／３）×ｚ］−３５８（℃）、［ただし、ｙ及びｚはそれぞれＦｅ２Ｏ３及びＺｎＯのモル％である。］
により計算で求めた。実施例のキュリー温度は２７０℃であった。
(Curie temperature)
Formula described in Ferrite (Maruzen Co., Ltd., published on November 30, 1986, 6th print, p. 79):
Tc = 12.8 × [y− (2/3) × z] -358 (° C.), [where y and z are mol% of Fe 2 O 3 and Zn O, respectively. ]
It was calculated by The Curie temperature of the examples was 270 ° C.
平板状の焼結体に対して、以下のように熱処理を行なった。図１に実施例の熱処理工程の温度条件を示す。熱処理は、室温から１．５時間で昇温させ、２５０℃に到達後１時間その温度で保持して、炉内の温度を安定させた後、１５０℃まで５℃／時間の降温速度で降温を行い、１５０℃未満の温度になった後、炉内に外気を導入して試料を冷却して行った。熱処理は大気中で行なった。 The flat plate-shaped sintered body was heat-treated as follows. FIG. 1 shows the temperature conditions of the heat treatment step of the example. In the heat treatment, the temperature is raised from room temperature in 1.5 hours, and after reaching 250 ° C., the temperature is maintained at that temperature for 1 hour to stabilize the temperature inside the furnace, and then the temperature is lowered to 150 ° C. at a cooling rate of 5 ° C./hour. After the temperature became less than 150 ° C., outside air was introduced into the furnace to cool the sample. The heat treatment was performed in the air.
熱処理工程後の平板状の焼結体を連続式ジョークラッシャーである前川工業所製ファインジョークラッシャー（登録商標）ＳＣ−１００７を用い、出口間隔２０ｍｍにて粗粉砕した。次いで粗粉砕粉を、振動篩機を用いて分級した。ここで、目開き１．４ｍｍの篩を用い、その篩を通過した粗粉砕粉を微粉砕した。 The flat plate-shaped sintered body after the heat treatment step was roughly pulverized using a continuous jaw crusher, Fine Joe Crusher (registered trademark) SC-1007 manufactured by Maekawa Kogyo Co., Ltd., at an outlet interval of 20 mm. The coarsely pulverized powder was then classified using a vibrating sieve. Here, a sieve having a mesh size of 1.4 mm was used, and the coarsely pulverized powder that passed through the sieve was finely pulverized.
微粉砕は、振動ミルを用いた。本実施形態では鉄製の球状メディアでバッチ式の振動ミルを用い１５分の粉砕時間で実施し微粉砕粉を得た。
次いで微粉砕粉を、振動篩機を用いて分級した。ここで、目開き１９８μｍの篩を用い、その篩を通過した微粉砕粉をＭｎＺｎ系フェライト粉とした。
このＭｎＺｎ系フェライト粉に対し、平板状の焼結体に行った熱処理と同じ熱処理を行うこともできる。
A vibration mill was used for fine pulverization. In this embodiment, a batch-type vibrating mill was used with an iron spherical medium for a crushing time of 15 minutes to obtain finely pulverized powder.
The finely ground powder was then classified using a vibrating sieve. Here, a sieve having an opening of 198 μm was used, and the finely pulverized powder that passed through the sieve was used as MnZn-based ferrite powder.
The MnZn-based ferrite powder can be subjected to the same heat treatment as that applied to the flat-plate sintered body.
得られたＭｎＺｎ系フェライト粉の粒度分布を図２に示す。図２は粒径（粒子径）（μｍ）を横軸とし、頻度（％）と通過分積算（％）とを縦軸として、粒度分布を示している。なお、縦軸は体積％である。この粒度分布は、レーザー回折散乱式粒度分布測定法にて堀場製ＬＡ−９２０を用い測定した。測定条件は以下の通りである。
＜透過率＞
・「最適レンジ上限」 ９５％ 、「最適レンジ下限」 ７０％
＜試料調整＞
・「循環速度」 １５（装置レンジ）
・「超音波作動時間」 ３分
・「超音波強度」 ７（装置レンジ）
＜測定条件設定＞
・「データ読み込み回数」 １０ 回
・「測定中超音波動作」 する
＜表示条件設定＞
・「分布形状」 標準
・「反復回数」 ３０ 回
・「相対屈折率」 ２．５０−４．００ｉ
・「粒子系基準」 体積
このＭｎＺｎ系フェライト粉は、平均粒径Ｄ５０（メジアン径）が５．１μｍであった。また、粒径１μｍの通過分積算（％）は、約１０％であった。
また、このＭｎＺｎ系フェライト粉の電子顕微鏡写真を図３に示す。得られたＭｎＺｎ系フェライト粉は、粒内破壊、粒界破壊の両方の破壊モードが混在した表面を有している。
The particle size distribution of the obtained MnZn-based ferrite powder is shown in FIG. FIG. 2 shows the particle size distribution with the particle size (particle size) (μm) as the horizontal axis and the frequency (%) and the accumulated passage amount (%) as the vertical axis. The vertical axis is volume%. This particle size distribution was measured using LA-920 manufactured by Horiba by a laser diffraction scattering type particle size distribution measurement method. The measurement conditions are as follows.
<Transmittance>
・ "Optimal range upper limit" 95%, "Optimal range lower limit" 70%
<Sample preparation>
・ "Circulation speed" 15 (equipment range)
・ "Ultrasonic operating time" 3 minutes ・ "Ultrasonic intensity" 7 (device range)
<Measurement condition setting>
・ "Data read count" 10 times ・ "Ultrasonic operation during measurement"<Display condition setting>
・ "Distribution shape" standard ・ "Number of repetitions" 30 times ・ "Relative refractive index" 2.50-4.00i
-"Particle-based standard" Volume This MnZn-based ferrite powder had an average particle size D50 (median diameter) of 5.1 μm. Moreover, the integrated amount (%) of the passing amount of the particle size of 1 μm was about 10%.
An electron micrograph of this MnZn-based ferrite powder is shown in FIG. The obtained MnZn-based ferrite powder has a surface in which both intragranular fracture and intergranular fracture fracture modes are mixed.
本実施例により、平均粒径Ｄ５０が１００μｍ以下のＭｎＺｎ系フェライト粉が得られた。本ＭｎＺｎ系フェライトは１〜５ＭＨｚの高周波数領域において、有用な材料であり、本ＭｎＺｎ系フェライト粉を用いた部品等の低損失化に有用なものとなる。 From this example, MnZn-based ferrite powder having an average particle size D50 of 100 μm or less was obtained. The MnZn-based ferrite is a useful material in a high frequency region of 1 to 5 MHz, and is useful for reducing the loss of parts and the like using the MnZn-based ferrite powder.
本発明のＭｎＺｎ系フェライト粉は、１〜５ＭＨｚの高周波数領域において使用される電子部品等に用いられる磁性体として、有用な材料となり得る。このＭｎＺｎ系フェライト粉は、樹脂等と混ぜられて、必要とされる形態に成形されて、磁心等として機能させることができる。このＭｎＺｎ系フェライトは、１〜５ＭＨｚの高周波数領域において優れた磁気特性を発揮するものであり、このＭｎＺｎ系フェライト粉を用いた部品等の低損失化に寄与することが期待できる。 The MnZn-based ferrite powder of the present invention can be a useful material as a magnetic material used for electronic parts and the like used in a high frequency region of 1 to 5 MHz. This MnZn-based ferrite powder can be mixed with a resin or the like and formed into a required form to function as a magnetic core or the like. This MnZn-based ferrite exhibits excellent magnetic characteristics in a high frequency region of 1 to 5 MHz, and is expected to contribute to reducing the loss of parts and the like using this MnZn-based ferrite powder.
Claims (6)
ＭｎＺｎ系フェライトの原料粉末を成形して成形体を得る成形工程と、
前記成形体を焼結し、１５０℃未満の温度まで冷却しＭｎＺｎ系フェライトの焼結体を得る焼結工程と、
得られたＭｎＺｎ系フェライトの焼結体を粉砕してＭｎＺｎ系フェライト粉を得る粉砕工程と、を備え、
更に、前記ＭｎＺｎ系フェライトの焼結体を熱処理する熱処理工程と、前記ＭｎＺｎ系フェライトの焼結体を粉砕したＭｎＺｎ系フェライト粉を熱処理する熱処理工程とのうち、少なくとも一方の熱処理工程を備え、前記熱処理工程が、
条件１：２００℃以上、及び
条件２：（Ｔｃ−９０）℃〜（Ｔｃ＋１００）℃［ただし、Ｔｃは前記ＭｎＺｎ系フェライトの主成分に含まれるＦｅ２Ｏ３及びＺｎＯのモル％から計算により求められるキュリー温度（℃）である。］
を満たす温度まで加熱し、一定時間保持した後、前記保持温度から５０℃／時間以下の速度で降温する熱処理工程であることを特徴とするＭｎＺｎ系フェライト粉の製造方法。 Fe 2 O 3 equivalent 53 to 56 mol% Fe, ZnO equivalent 3 to 9 mol% Zn and MnO equivalent residual Mn as main components, total 100 parts by mass of the main components in terms of oxides On the other hand, it is a method for producing MnZn-based ferrite powder containing 0.05 to 0.4 parts by mass of Co as a sub-component in terms of Co 3 O 4 .
The molding process of molding the raw material powder of MnZn-based ferrite to obtain a molded product,
A sintering step of sintering the molded product and cooling it to a temperature of less than 150 ° C. to obtain a sintered body of MnZn-based ferrite.
A pulverization step of pulverizing the obtained MnZn-based ferrite sintered body to obtain MnZn-based ferrite powder is provided.
Further, the heat treatment step of at least one of a heat treatment step of heat-treating the sintered body of the MnZn-based ferrite and a heat treatment step of heat-treating the MnZn-based ferrite powder obtained by crushing the sintered body of the MnZn-based ferrite is provided. The heat treatment process
Condition 1: 200 ° C. or higher, and Condition 2: (Tc-90) ° C. to (Tc + 100) ° C. [However, Tc is calculated from the molar% of Fe 2 O 3 and Zn O contained in the main component of the MnZn-based ferrite. Curie temperature (° C). ]
A method for producing MnZn-based ferrite powder, which comprises a heat treatment step of heating to a temperature satisfying the above conditions, holding for a certain period of time, and then lowering the temperature from the holding temperature at a rate of 50 ° C./hour or less.
前記高温保持工程は、保持温度が１０５０℃超１１５０℃未満で、雰囲気中の酸素濃度が０．４〜２体積％であり、
前記降温工程中、９００℃から４００℃まで降温させる際の酸素濃度を０．００１〜０．２体積％の範囲とし、（Ｔｃ＋７０）℃から１００℃までの間の降温速度を５０℃／時間以上とする、請求項１〜４のいずれかに記載のＭｎＺｎ系フェライト粉の製造方法。 The sintering step includes a temperature raising step, a high temperature holding step, and a temperature lowering step.
In the high temperature holding step, the holding temperature is more than 1050 ° C and less than 1150 ° C, and the oxygen concentration in the atmosphere is 0.4 to 2% by volume.
During the temperature lowering step, the oxygen concentration when lowering the temperature from 900 ° C. to 400 ° C. is in the range of 0.001 to 0.2% by volume, and the temperature lowering rate between (Tc + 70) ° C. and 100 ° C. is 50 ° C./hour or more. The method for producing an MnZn-based ferrite powder according to any one of claims 1 to 4.
The method for producing MnZn-based ferrite powder according to claim 5, wherein the temperature lowering rate between the holding temperature and 100 ° C. is 50 ° C./hour or more during the temperature lowering step.
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| JP2020202348A (en) * | 2019-06-13 | 2020-12-17 | 日立金属株式会社 | Method for manufacturing manganese zinc-based ferrite powder |
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| CN115010480A (en) * | 2022-07-04 | 2022-09-06 | 娄底市玖鑫电子科技有限公司 | Preparation method of manganese-zinc ferrite KAH100 material |
| CN115650718A (en) * | 2022-11-18 | 2023-01-31 | 浙江工业大学 | Manganese-zinc ferrite material with ultra-wide temperature, low power consumption and magnetic conductivity and temperature stability and preparation method thereof |
| WO2024103757A1 (en) * | 2022-11-17 | 2024-05-23 | 横店集团东磁股份有限公司 | Power ferrite material, preparation method therefor, and use thereof |
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| CN115650718A (en) * | 2022-11-18 | 2023-01-31 | 浙江工业大学 | Manganese-zinc ferrite material with ultra-wide temperature, low power consumption and magnetic conductivity and temperature stability and preparation method thereof |
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